The invention relates to an adjustment device for adjusting several guide vanes of an engine.
In engines, for example turbomachines and in particular gas turbine engines, it is generally known to provide adjustable guide vanes for influencing the flow depending on the rotational speed of rotating rotor blades. In particular in gas turbine engines, usually adjustable guide vanes are used in the area of the compressor, wherein the guide vanes are adjusted depending on the compressor's rotational speed. In the technical jargon, the adjustable guide vanes are referred to as variable stator vanes, or VSV, in short.
Here, the adjustable guide vanes usually represent a component of a guide vane row and are arranged inside a housing in which the rotating rotor blades are also arranged. In practice, the individual guide vanes are mounted at the housing so as to be respectively adjustable via a bearing journal. Provided inside the housing is usually a rotatable bearing of a guide vane at a hub, e.g. of a compressor. Each bearing journal is mounted in a rotatable manner at the housing inside an associated bearing opening in the wall of the housing. At that, the bearing journal passes through this bearing opening along an extension direction of the bearing journal, so that an end of the bearing journal is accessible at an outer side of the housing for adjusting the corresponding guide vane by turning the bearing journal. At that, usually respectively one lever, which is fixated at an adjusting element in the form of an adjusting ring of an adjusting mechanism, engages at a journal end to simultaneously adjust several guide vanes by adjusting the adjusting element and multiple levers that are hinged thereat. Such a generic guide vane assembly with adjustable guide vanes for a compressor of a gas turbine engine is shown EP 2 949 878 A1, for example. In practice, the bearing journals of the guide vanes, which are often also referred to as shingles, are provided in radially protruding sleeve-shaped bearing extensions of the housing. These bearing extensions are formed at a wall of the housing and ensure the rotatable mounting and support of the bearing journal.
The at least one adjusting element of the adjustment device provided for adjusting the guide vanes is usually supported at an outer side of the housing, and is adjustable relative to the same in the circumferential direction so as to cause a rotation of the guide vanes about their respective rotational axis. The adjusting element is coupled to a connection element of the adjustment device, for example connected to the same in a hinged manner, with the connection element of the adjustment device in turn being additionally connected to a crank shaft of the adjustment device. This crank shaft is configured and provided for controlling an adjusting movement of the adjusting element, and can be rotated for that purpose about a longitudinal axis of the crank shaft by means of an actuator. The crank shaft has at least one coupling element which is coupled to the connection element and at which the connection element is hinged in order to transform a rotational movement of the crank shaft into an adjusting movement of the adjusting element for adjusting the guide vanes.
Here, the crank shaft usually has several coupling elements that are arranged at a distance to each other along the longitudinal axis, with respectively one connection element for an associated adjusting element being hinged thereat. In this way, several adjusting elements can be synchronously adjusted by means of the rotation of the crank shaft, and thus guide vanes of several guide vane rows can be adjusted. At that, it is determined through the position of the individual coupling elements as to what adjustment track the respectively associated adjusting element, which is coupled via a connection element, covers when the crank shaft is rotated by a defined rotational angle. In this context, it is also often important at what radial distance to the centrally extending longitudinal axis of the crank shaft the respective connection element is hinged at its associated coupling element. The arrangement of the individual coupling elements and in particular their radial position ultimately influences the possible adjustment of the guide vanes, and in particular the degree of the adjustment of the guide vanes of different guide vane rows, which have to be coordinated with each other. If the optimal position and relative position of the individual coupling elements is known, a single-piece crank shaft at which the individual coupling elements are formed is usually used. However, here an adjustment of the possible adjustment tracks is no longer possible, or is possible only to a very limited degree.
In particular to be able to still variably adjust components of the crank shaft during the development phase of the engine and in particular to be able to vary the radial position of individual coupling elements for adjusting an adjusting element in the form of an adjusting ring for a guide vane row, what is for example suggested in EP 2 949 878 A1 is to fixate the individual coupling elements, which are preferably embodied with fork heads, at a solid shaft by means of a spline connection, so that the radial position of these coupling elements can be changed. It is also provided that the coupling element can be fixated at the solid shaft at an axial end of the crank shaft in different rotational positions. What is suggested for this purpose are two bolted connections through two threaded bolts, wherein one of the bolted connections can be realized by means of different bolt openings that are arranged next to each other along a circular line about the longitudinal axis.
While in this way the adjustment device as it is known from the state of the art already offers a certain degree of flexibility when it comes to setting the crank shaft for the adjusting movement of the adjusting element that is to be obtained, the modification of a transmission ratio and also the range of the adjusting options of the coupling elements in the radial direction are limited in the adjustment device of EP 2 949 878 A1.